An apparatus for discriminating between liquids having differing thermal conductivities includes a thermally conductive substrate, a resistor and a thermistor mounted to the thermally conductive substrate. Two leads on the resistor enable a current to be passed through the resistor to generate heat, and two leads on the thermistor enable a current to be passed through the thermistor to generate a datum indicative of thermistor temperature. An electrical insulator encapsulates the resistor, the thermistor and part of the thermally conductive substrate. A remainder of the thermally conductive substrate may extend beyond the electrical insulator to provide a thermal path from the resistor and thermistor to a liquid in which the apparatus may be immersed.

A fluid level sensing device includes a substrate (210) and a sensing die (216) cantilevered at one end from the substrate. A number of sensing components (218), preferably thermal or impedance sensing components, are disposed on the sensing die and detect a fluid level in a fluid reservoir. A protective member (208) is also cantilevered at one end from the substrate alongside the sensing die. Electrical interconnects (212) output data collected from the number of sensing components. A number of sensing dies may be provided to lengthen the sensing device, in which case the protective cover extends alongside and parallel to the number of sensing dies.

A method of detecting a level of printable fluid in a container includes, with at least one sensing location on a die in thermal contact with the printable fluid in the container, sensing a voltage of a capacitor over time as current from the capacitor leaks through a field effect transistor (FET). The FET and capacitor are associated with the sensing location. The method may further include, based on the voltage of the capacitor over time and a threshold voltage, determining whether the printable fluid is present at the at least one sensing location.

In one example in accordance with the present disclosure a liquid level sensing device is described. The device includes a carrier and a liquid level sensing device disposed on the carrier. The liquid level sensing interface has an aspect ratio of at least 1:50. A number of liquid level sensing components are disposed on the liquid level sensing interface. The number of liquid level sensing components detect a liquid level in a liquid container. The liquid level sensing device also includes an electrical interconnect to output data collected from the number of liquid level sensing components.

An example printing cartridge includes a sensing die including a plurality of sensing locations in thermal contact with a fluid container, an on-die controller to select a sensing location of the plurality of sensing locations to activate and to provide a variable threshold voltage, and a voltage comparator to compare a sensed voltage generated at a selected sensing location to the variable threshold voltage, and output time-based information based on the comparison, the time-based information representative of whether a fluid is present at a fluid level associated with the selected sensing location.

A fluid sensor system detects one or more performance characteristics of a heating system that heats a fluid. The sensor system includes a probe having a finite length a portion of which is to be immersed in the fluid. The probe includes a resistive heating element and a fluid temperature sensor for measuring one or more performance characteristics, wherein the fluid temperature sensor is configured to measure a fluid temperature, and the resistive heating element is operable as a heater to create a temperature differential between the fluid and air to detect the fluid, and as a sensor to measure a fluid level.

An electronic liquid level gauge assembly includes an electronic display located in a housing connected to a tank. The display has first and second display portions for indicating liquid level condition. A first electronic sensor senses a change in magnetic field of a magnet associated with a liquid level transducer, with magnet rotation being proportional liquid level change. A processor determines a temperature-compensated liquid level condition by correlating the liquid level signal with temperature measurement of the liquid. A temperature-compensated vapor space can also be calculated based on tank information and properties of the liquid. Signals related to the temperature-compensated liquid level and vapor space are sent to the display and wirelessly transmitted to a smart phone or the like for remotely viewing the tank information. The smart phone also includes a special app for sending information, firmware updates, and display configuration data to the electronic gauge assembly.

In some examples, a liquid container comprises a chamber forming a volume containing a liquid, an elongated strip extending into the volume containing the liquid, the strip supported along a side of the volume such that a face of the strip adjacent the side of the volume is not opposed by the liquid, a plurality of heaters supported by the strip along the strip, and a plurality of temperature sensors supported by the strip along the strip.

A sensor for determining liquid level in a liquid reservoir can include a primary inductor and a secondary inductor to be associated with sides of the reservoir that changes shape as a volume of liquid changes or is displaced within the liquid reservoir. The sensor can include an electrical power source to inductively couple the primary inductor and the secondary inductor. The liquid level sensor can include an inductive coupling measurement device associated with the primary inductor and/or the secondary inductor to measure a characteristic indicative of the inductive coupling of the primary inductor and the secondary inductor (e.g., a distance between inductors). As liquid volume changes and the reservoir deforms, the inductors move relative to each other and a voltage change occurs to determine a liquid level in the reservoir. A sensor kit is provided.

A liquid level sensor, a method for controlling the same, and a reactor with the same are provided. The liquid level sensor includes a first mounting base and a cable assembly. The cable assembly includes a metal shell disposed on the first mounting base; a heating element for heating the metal shell; and a temperature detector for detecting a temperature of the metal shell.